Electrostatic telecommunication system



Jan. 5, 1931. w. G. H. FINCH ELECTROSTATIC TELECOMMUNICATION SYSTEM Filed April 1, 1936 TELEPICTURE TRANSMITTER COMPENSATION NETWORK Fig.5

William PHONE I BOX 20/ 2/ INVENTOR.

ATTORNEY.

Patented 1.... s, 1937 PATENT OFFICE- ELECTROSTATIC TELECOMDIUNICATION SYSTEM.

William G. n. Finch, New York, N. 1!.

Application April 1, 1936, Serial No. 72,039

Claims.

- This invention relates to telecommunication systems and more particularly relates to novel apparatus for and method of transmission of pictures to remote points over telephone systems,

5 and is a division of the co-pending parent ap-' plicatlon Serial No. 65,869.

The widest use which telepicture systems today enJoy is in connection with newspaper service, where pictures of important news events are transmitted from or near its source to newspaper ofllces for publication. For such use, it is highly desirable that the picture be transmitted as near to the scene as practicable. Heretofore it has been proposed to use telephone lines which are usually available at almost any place for the transmission of pictures. 'Inasmuch as the telephone company, however, does not permit any interconnection by a subscriber to its line, it has been necessary to find some other than physical *0 connection means for transmitting picture signals over the telephone lines. It has been proposed that this might be accomplished by acoustic coupling to the telephone line. Such a system comprised a loud speaker unit which transiormed 25 picture signals into corresponding sound, which in turn were impinged on the usual telephone microphone.

In the parent application is disclosed an electromagnetic induction system for transmitting and receiving telepicture signals over a telephone line without physical interconnection to the telephone system. By utilizing a compensation network designed to correct the overall transmission characteristics, it has been shown in this appli- 35 cation how a linear frequency transmission characteristic may be effected with the electromag: netic induction system. My present invention contemplates the electrical induction of telecommunication signals, particularly telepicture sig- 40 nals, by electrostatic means over a telephone system. This invention is particularly applicable to portable telepicture transmitters as will be hereinafter described. The reception of the telepicture signals at the receiving station is prefer- 5 ably accomplished. by, the electromagnetic induction means described in my parent application or any other method.

It is accordingly an object of my present invention to provide novel methods of and ap- 50 paratus for electrically coupling to telephone systems for the transmission and reception of signals between remote points. v

Another object of my invention is to provide a novel methods of and apparatus for transmitting 55 pictures over a telephone system.

A further object of my invention is to provide novel methods of and apparatus for electrostatically coupling a telepicture transmitter to a telephone station for transmitting telepicture signals without physical interconnection thereto.

Still another object of my invention is to provide novel methods of and apparatus for electrostatically coupling a telepicture transmitter to a telephone system for transplanting telepicture signals with a substantially linear frequency transmission characteristic.

These and further objects of my invention will become apparent in the following description taken in connection with the drawing, in which:

Figure l is a diagrammatic representation of the electrostatic induction system in accordance with my present invention.

Figures 2 and 3 are modifications of the electrostatic coupling transmission system as applied to a portable transmitter.

Referring to Figure 1, telepicture transmitter ill schematically represents an electrical generator of picture or facsimile signals in accordance with the elemental shading of a picture to be transmitted. Transmitter i0 contains sufllcient electronic amplification to provide a sult-' able energy level at the output ll-l2. The out put stage of transmitter I0 is preferably designed for a high voltage output. A high voltage'telepicture output II and I2 improves the electrostatic signal induction whereby a stronger signal is induced into the telephone system. A compensation network I3 is connected at the output I l-l2 of transmitter Ill for the purpose to be hereinafter explained.

Connections l4 and I5 at the output of compensation network l3 connect the telepicture signals to be transmitted to the metallic plate l6 and to ground respectively. Metallic plate I6 is preferably a copper or aluminum plate and is insulated and isolated from ground.

Metallic plate l6 being connected to the high voltage terminal l4 will be placed at a varying electrostatic potential with respect to ground in accordance with the'telepicture signals to be transmitted as they are in turn affected by compensation network l3. In Figure l, I have illustrated a hand set automatic telephone l'l|8 at the transmission station of the telephone system. The telephone base l1 and hand set iii are placed upon the induction plate l6. Telephone il-lil is connected by telephone cable iii to the phone box 20. The output lines 2l-22 of phone box are connected to the central station for interconnection with an optional receiving station in a well known manner.

The telephone station "-48 is placed in operative connection with the desired telephone receiving station, generally at the central newspaper omce, or other station where a telepicture translating apparatus is located. No physical interconnection with the telephone system is made in accordance with the present invention. Station to station interconnection and speech communication is carried on in the usual manner. After establishing telephone connection preliminary instructions and operating adjustments are effected and picture transmission is started.

The metallic plate i6 is electrostatically energized by telepicture transmitter H) at a preferably high potential with respect to ground, electrostatically induces corresponding telepicture signals into the telephone lines 2l-22. The electrostatic induction action is due to a condenser or intercapacitive action between the telephone station i|-l8 and the metallic plate l6. Although I have illustrated hand set I8 upon plate l6, very satisfactory results are obtained by electrostatic induction across the telephone .the telephone system itself.

base I! alone.

I have found that the frequency characteristics of the electrostatic induction method of my which corresponds to the schematically illus-- trated telepicture transmitter ill of Figure 1. A transmitter 23 contains the necessary signal generating and amplifying equipment and the metallic plate l6 set into a central opening in the cover plate 24. It must be understood that plate I8 is insulatingly supported on cover 24 which is preferably wood, hard rubber or other suitable composition or dielectric material. Although the hand set I8 is illustrated in a position of! plate l6, it will be evident that the exposed portion of plate l6 may be made sufllciently large to provide room for hand set i8. Although I have illustrated in these modifications, a hand set telephone station, it is to be understood that other types of movable telephone systems are equally employable with my present invention.

Figure 3 is a further modification of my invention in connection with a portable transmitter 25. A compartment 26 is provided at one end of the transmitter cabinet 25 for housing the telephone I 1. Although a hand set I8 is illustrated without the compartment 26, it may readily be placed therein although it is not necessary. The interior of compartment 26 is lined with metallic plate 21 to provide the electrostatic coupling means corresponding to plate I6 of Figures 1 and 2. A more effective electrostatic or intercapacitive effect is had with the all-enclosing compartment 28 in accordance with this modification. It is to be understood that the metallic lining 21 is isolated from ground and is supported by insulation or dielectric material '2.

of which the cabinet 28 is preferably constructed.

Although I have illustrated my invention in connection with a movable telephone station, it will be evident to those skilled in the art that my invention is applicable to a stationary telephone station such as is generally used in public telephone booths. A metallic plate corresponding to plate It, not necessarily flat, but designed to enclose a substantial portion of such a telephone station may be electrically connected to the output of the telepicture transmitter for electrostatically inducing the signals across such a telephone station.

The electrostatic inducing methods hereinabove described make it possible for a portable telepicture transmitter to transmit a picture which may have immediate news value from any telephone station to the central newspaper plant by merely establishing a telephone connection between the stations, verbally establishing the condition of the transmission, and proceeding to transmit the picture in a manner already described. The tremendous commercial advantage, particularly to newspaper offices, of such an arrangement is self-evident. No permanent leasing of telephone lines between permanent stations is required. Payment for the use of the line is according to the actual time taken in transmitting the picture instead of over a twenty-four hour period as is at present required.

I claim:

1. In a telepicture system, means for generating electrical signals of relatively high voltage in accordance with a picture to be transmitted;-

a cabinet housing said signal generating means; a metallic member; said member being insulatingly mounted in said cabinet; means for electrically impressing said signals on said member; and a telephone system comprising a telephone station; said member and said telephone station being electrostatically coupled for inducing said signals into said telephone system.

2. In a telepicture system, means for generating electrical signals of relatively high voltage in accordance with a picture to be transmitted; a cabinet housing said signal generating means; a metallic member; said member being insulatingly mounted in said cabinet; means for electrically impressing said signals on said member; a telephone system comprising a telephone station; said member and said telephone station being electrostatically coupled for inducing said signals into said telephone system; and a compensation network connected in' said first men.- tioned means.

3. In a. telepicture system, means for generating electrical signals in accordance with a picture to be transmitted; a cabinet housing said signal generating means; a metallic member; a telephone system comprising a telephone station; a compartment in said cabinet for said telephone station; said member and said telephone station being electrostatically coupled for inducing said signals into said telephone system; and a compensation network connected in said first mentioned means.

4. In a telepicture transmitter employing a telephone line having a telephone with a metallic base portion: means for generating carrier wave signals of relatively high voltage modulated by picture currents to be transmitted; a cabinet housing said signal generating means: and a metallic plate insulatingly mounted within said cabinet and electrically connected to the output of said signal generating means for supporting n said telephone at its metallic base portion for electrostatically inducing said signals into said telephone line across said telephone base.

5. In a telepicture transmitter employing a telephone line having a telephone with a metallic base portion: means for generating carrier wave signals of relatively high voltage modulated by a picture currents to be transmitted; a cabinet housing said signal generating means; a metallic 10 plate insulatingly mounted within said cabinet and electrically connected to the output of said signal generating means for supporting said telephone at its metallic base portion for electrostatically inducing said signals into said telephone line across said telephone base; and a compensation network associated with said signal generating means for correcting the frequency characteristic of the signals induced into said telephone line.

WILLIAM G. H. FINCH. 

